In recent years, microchannel chips have been used to accurately and speedily analyze a trace substance such as protein and nucleic acid. Microchannel chips advantageously allow the amount of reagents or samples to be small, and are expected to be used for various uses such as laboratory tests, food tests, and environment tests.
It has been proposed to provide a stop valve in a channel of a microchannel chip to stop liquid to be analyzed at a predetermined position in the microchannel chip (see, for example, PTL 1).
The microchannel chip disclosed in PTL 1 includes a channel through which liquid to be analyzed flows, an introduction part disposed on the upstream side of the channel and configured to introduce the liquid to the channel, a discharging part disposed on the downstream side of the channel and configured to discharge the liquid from the channel, and a stop valve disposed in the channel and configured to control the movement of the liquid in the channel. The stop valve is configured by providing a constricted part in the cross section of the channel that is perpendicular to the travelling direction of the liquid.
In the microchannel chip disclosed in PTL 1, liquid is dropped to the introduction part to fill the channel with liquid by capillarity. When the leading end of the advancing liquid reaches the stop valve, the channel is filled with the liquid from the introduction part to the stop valve. At this time, the leading end of the liquid forms a uniform interface because of the stop valve.